Messages in this thread | | | Date | Thu, 2 May 2002 14:28:10 -0700 | From | William Lee Irwin III <> | Subject | Re: Bug: Discontigmem virt_to_page() [Alpha,ARM,Mips64?] |
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On Thu, May 02, 2002 at 08:41:36PM +0200, Andrea Arcangeli wrote: >> I believe 64-bit PCI is pretty much taken to be a requirement; if it >> weren't the 4GB limit would once again apply and we'd be in much >> trouble, or we'd have to implement a different method of accommodating >> limited device addressing capabilities and would be in trouble again.
On Thu, May 02, 2002 at 03:20:39PM -0700, Martin J. Bligh wrote: > IIRC, there are some funny games you can play with 32bit PCI DMA. > You're not necessarily restricted to the bottom 4Gb of phys addr space, > you're restricted to a 4Gb window, which you can shift by programming > a register on the card. Fixing that register to point to a window for the > node in question allows you to allocate from a node's pg_data_t and > assure DMAable RAM is returned. > M.
Woops, I forgot about the BAR, thanks. Heck, IIRC you were even the one who told me about this trick.
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